Dry Rot & Wet Rot: How to Identify & Repair
Wet rot, caused by the fungus Coniophora puteana, grows on wet or damp timbers, but does not spread unless an entire timber is wet.
Wet rot is considered less harmful to wood because it only affects the damp parts of wood. In other words, the fungus remains localized in one area, without spreading, unless the entire piece of timber is excessively damp. The infection often appears in timber with a moisture content of around 50%. The fungus can also cause decay in plaster, wallpaper, and carpets. Coniophora puteana causes brown-rot in both hardwood and conifer wood, including building timbers and anywhere else wood is used. The fungus starts as small patches that can develop into extensive, fleshy masses that attach tightly to the timber. The surface is smooth and soft, first appearing white in color before turning a dark brown color.
- Brown fungus may appear on timber
- Timber is likely to feel soft and spongy with discoloration present
- Timber will dry out and crack or crumble
- Paint on timber may be visibly deteriorated
Dry rot, caused by the fungus Serpula lacrymans, is more harmful because it can easily spread throughout wood timbers.
Like wet rot, S. lacrymans affect wood that is wet or damp. But the spores engulf the entire timber regardless of moisture content. Even if the wood is only damp in one spot, dry rot can still spread to the non-damp parts of the wood. The fungus breaks down cellulose and hemicellulose, leaving behind wood that is spongy to the touch and visibly deteriorated.